"We hope this fluid will offer a viable solution to a significant problem, both on and off the battlefield," said Dr Mitchell Fink, a professor of critical care medicine who led the study.

He said that haemorrhagic shock, an umbrella term to describe how the body reacts to losing massive quantities of blood, was usually treated by controlling the bleeding and restoring the blood's volume with a lactate solution and packed red blood cells.

This aloe vera option could be an alternative if its success in rats could be translated to humans.

"Soldiers wounded in combat often lose significant amounts of blood, and there is no practical way to replace the necessary amount of blood fast enough on the front lines. When this happens, there is inadequate perfusion of the organs which quickly leads to a cascade of life-threatening events," Fink said.

"Medics would need only to carry a small amount of this solution, which could feasibly be administered before the soldier is evacuated to a medical unit or facility."

Juice derivative alters fluid properties

The researchers, who received funding from the Defense Advanced Research Projects Agency, tested a substance derived from the mucilage inside aloe leaves, a substance rich in polysaccharides that affect the qualities of fluid.

The substance makes fluid more viscous, thus reducing the resistance to turbulent flow, the researchers said.

"As a drag-reducing polymer, it may provide better diffusion of oxygen molecules from red blood cells to tissues because of its ability to better mix in the plasma surrounding red blood cells," said Associate Professor Marina Kameneva, an expert in artificial blood who worked on the study.

They tested rats, injecting them either with the aloe derivative or salt solution after draining them of some blood.

In a second experiment involving more blood loss, five of 15 rats survived for two hours after getting aloe compared to one of 14 treated with saline solution alone. Seven animals receiving no treatment all died within 35 minutes.